<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    div {
      border: solid 1px #161;
      height: 100px;
      width: 100px;
      display: flex;
      align-items: center;
    }
  </style>
</head>

<body>
  <div>
    <span>flex垂直需要考虑兼容性</span>
  </div>
</body>

</html>